An elevator consists of at least one elevator car which is vertically movable in a shaft and receives passengers in order to move these to a desired floor of a building. In order to be able to exercise this task the elevator usually has at least one of the following elevator components: a drive, deflecting rollers, traction elements, a counterweight and a respective pair of rails for guidance of an elevator car and a counterweight.
In that case the drive produces the power required for transport of the passengers present in the elevator car. An electric motor usually looks after this function. This directly or indirectly drives a drive pulley disposed in friction contact with a traction element. The traction element can be a belt or a cable. It serves for suspending as well as conveying an elevator car and a counterweight, which are both suspended in such a manner that the gravitational forces thereof act in opposite direction along the traction element. The resulting gravitational force which has to be overcome by the drive correspondingly substantially reduces. In addition, due to the greater contact force of the traction element with the drive pulley a greater drive moment can be transmitted from the drive pulley to the traction element. The traction element is guided by deflecting rollers.
Optimum utilization of the shaft volume has ever increasing significance in elevator construction. Particularly in high-rise buildings with a high degree of utilization of the building the most efficient possible management of the passenger traffic for a given shaft volume is to be sought. This objective can be achieved firstly by an optimum space-saving arrangement of the elevator components, which creates room for larger elevator cars, and secondly by elevator concepts which enable vertical movement of several independent elevator cars in one shaft.
An elevator with at least two elevator cars disposed one above the other in the same shaft is known from EP 1 489 033. Each elevator car has an own drive and an own counterweight. The drives are arranged near first and second shaft walls and the counterweights are also suspended near first or second shaft walls in each instance below the associated drive at driving or holding cables. The axes of the drive pulleys of the drives are perpendicular to first and second shaft walls. The two independently movable elevator cars guarantee a high transport performance. The positioning of the drives in the shaft near first or second walls makes a separate engine room redundant and enables a space-saving compact arrangement of the drive elements in the shaft head.